There are no disadvantages to trying a different phono pre amp. What are your expectations?

You don't say which VA pre amp you own. You don't mention the cartridge you would be using. The Ortofon Red, I assume. You don't mention your audio priorities; what you value and what you can forgive. You don't mention the turntable set up or that of the rest of the system. You don't even mention the rest of the system. Lacking any of those bits of information the response can be not much more than a "suck it and see what comes out" reply.

What seems to be lacking from virtually every discussion of turntables today is the ol' "garbage in = garbage out" concept of system building. There has for the last four decades at least been an accepted hierarchy in building a system with the most musical satisfaction as your goal. In fact, how to achieve superior performance from a table isn't really discussed at all. Tables are "cool" and "retro" and that seems to be the end of the discussion. How to get the most performance from a table is not even secondary, it isn't discussed at all. Which leaves me wondering just what the newest buyers of turntables really expect from their systems.

Beginning in the late '70's Linn became THE turntable to own by by demonstrating the superior musical performance of a high quality, well set up turntable with a medium quality arm matched carefully to the table and a low cost, but musically decent, cartridge when compared to an expensive but poorly thought out table with a mediocre arm and an expensive cartridge. In other words, a musically adept $50 cartridge in a $400 table/arm combination will almost always outperform a $500 cartridge installed in a $250 table and arm. Just as inexpensive speakers which portray music as an event will draw the most information from high end separates vs expensive speakers working from a mediocre receiver. Garbage in = garbage out. Nothing can put information back into the signal once it has been lost and nothing in a high quality system can minimize the distortions created by inferior equipment placed at the front of the system.

Vinyl playback is all about vibrations and minimizing external and internal vibrations is the point of a high quality table/arm combination. The first step in that process is the support system for the table, which will determine how much external resonance is allowed into the table and how much internal vibration is drained away from the table. I can all but guarantee any turntable plopped down because that's where it fits will be in the most unfavorable location for any turntable let alone an unsuspended table like the Pro-Ject. Next the table itself must meet certain requirements of minimizing resonances and distortions while maximizing information retrieval.

Next comes the tonearm, which is either a damped or an undamped system. Improving the tonearm is, in the hierachical system concept, a more important improvement than is a cartridge upgrade. Finally, the cartridge is given consideration and it too must be both a good mechanical match and an electrical fit with the turntable and the phono pre amp. However, the cartridge itself can only perform to the level allowed by the table and then the arm. Therefore, the system's musical abilities depend first upon the support system for the table, then the table itself, the arm next and, finally, the cartridge.

If that "system" approach is ignored, then the resulting performance of the combined components will be downgraded. In a pre-packaged system such as the Debut table, you have to assume the designer has made many of the selections which are appropriate, but you still must consider the table's set up as vital to the quality of reproduction. It would, therefore, make more sense to invest in a high quality support shelf before you tried a new pre amp. Given the performance level and limits of the Debut and its arm, you probably are locked into the O.E.M. arm. Upgrading the table would make more sense than placing a higher quality arm on the Debut. Given the Debut arm, it can support a somewhat higher quality cartridge than the Red. But it is also quite easy to buy too much cartridge for the Debut arm. A higher quality cartridge would be the more appropriate choice before you began upgrading or even experimenting with a new phono pre amp. That, IMO, is the best - and the correct - way to go about your purchases.

You have though neglected to say which pre amp you might try. That puts us back at square one and the recommendation to simply try a pre amp. The new stand alone pre amps have much going for them that a built in pre amp sitting along side other circuitry and a good sized power transformer inside an all in one pre amp can't technically match. If you decide to try a new pre amp, make sure it is a good electrical match for the line level inputs to your Van Alstine and a good electrical match to the cartridge. Too many buyers ignore the technically correct aspects of system building and buy whatever sounds good in a review. That's a very shortsighted and lazy way to build a system IMO.

Know your priorities well since any budget line equipment will have trade offs. Don't mistake different for better. A component is most often judged to be "better" when it has sins of omission rather than sins of commission. The VA pre amps possess a rather certain personality. If the rest of the components in front of the VA are in opposition to the character of the VA, then you end up with a muddled sound. And, of course, an out board pre amp will require interconnects. Cables with high capacitance should be avoided in a phono interconnect though that is not as important when you are working from the line out of a phono pre amp. But remember your selection of cables will likely influence your feelings about the performance of the out board pre amp.

Otherwise, if you've paid attention to all the details leading up to the phono pre amp, your best bet is to give one of the newest designs a try. You should have little to lose other than some time and possibly some return shipping charges.